Abstract: A method, apparatus, and a non-transitory computer-readable storage medium for decoding a video signal are provided. In one method, a decoder may receive constraint flags, and at least one of the constraint flags indicates whether a slice is an intra slice. The decoder may obtain prediction samples based on the at least one of the constraint flags.

Abstract: Systems, methods, and instrumentalities are disclosed for motion vector clipping when affine motion mode is enabled for a video block. A video coding device may determine that an affine mode for a video block is enabled. The video coding device may determine a plurality of control point affine motion vectors associated with the video block. The video coding device may store the plurality of clipped control point affine motion vectors for motion vector prediction of a neighboring control point affine motion vector. The video coding device may derive a sub-block motion vector associated with a sub-block of the video block, clip the derived sub-block motion vector, and store it for spatial motion vector prediction or temporal motion vector prediction. For example, the video coding device may clip the derived sub-block motion vector based on a motion field range that may be based on a bit depth value.

Abstract: An electronic apparatus performs a method of decoding video data.

Abstract: Methods and devices are provided for reducing the decoding latency introduced by luma mapping with chroma scaling (LMCS). In one method, during decoding of a coding unit (CU) that is coded by an inter mode or Combined Inter and Intra Prediction (CIIP) mode under LMCS framework, a plurality of reconstructed samples of luma component is obtained in a mapped domain, a plurality of converted samples of luma component is obtained in an original domain by converting the plurality of reconstructed samples of luma component from the mapped domain into the original domain, and the plurality of converted samples of luma component is used in the original domain, without clipping, in deriving chroma scaling factors for decoding the chroma samples of the CU.

Abstract: Systems and methods are described for reducing the complexity of using bi-directional optical flow (BIO) in video coding. In some embodiments, bit-width reduction steps are introduced in the BIO motion refinement process to reduce the maximum bit-width used for BIO calculations. In some embodiments, simplified interpolation filters are used to generate predicted samples in an extended region around a current coding unit. In some embodiments, different interpolation filters are used for vertical versus horizontal interpolation. In some embodiments, BIO is disabled for coding units with small heights and/or for coding units that are predicted using a sub-block level inter prediction technique, such as advanced temporal motion vector prediction (ATMVP) or affine prediction.

Abstract: A method for video coding is provided. The method includes obtaining a first reference picture and a second reference picture associated with a current prediction block, obtaining a first prediction L0 based on a first motion vector MV0 from the current prediction block to a reference block in the first reference picture, obtaining a second prediction L1 based on a second motion vector MV1 from the current prediction block to a reference block in the second reference picture, determining whether a bidirectional optical flow (BDOF) operation is applied, and calculating a bi-prediction of the current prediction block based on the first prediction L0 and the second prediction L1, and first gradient values and second gradient values.

Abstract: Methods and devices are provided for reducing the decoding latency introduced by LMCS. In one method, during decoding of a coding unit (CU), a plurality of reconstructed luma samples is selected from a first pre-determined region neighboring to a second pre-determined region where the CU is located, an average of the plurality of reconstructed luma samples is calculated, and the average of the plurality of reconstructed luma samples is used directly, without any clipping, in deriving a chroma residual scaling factor for decoding the CU.

Abstract: Systems and methods are described for reducing the complexity of using bi-directional optical flow (BIO) in video coding. In some embodiments, bit-width reduction steps are introduced in the BIO motion refinement process to reduce the maximum bit-width used for BIO calculations. In some embodiments, simplified interpolation filters are used to generate predicted samples in an extended region around a current coding unit. In some embodiments, different interpolation filters are used for vertical versus horizontal interpolation. In some embodiments, BIO is disabled for coding units with small heights and/or for coding units that are predicted using a sub-block level inter prediction technique, such as advanced temporal motion vector prediction (ATMVP) or affine prediction.

Abstract: Systems and methods are described for video coding using affine motion models with adaptive precision. In an example, a block of video is encoded in a bitstream using an affine motion model, where the affine motion model is characterized by at least two motion vectors. A precision is selected for each of the motion vectors, and the selected precisions are signaled in the bitstream. In some embodiments, the precisions are signaled by including in the bitstream information that identifies one of a plurality of elements in a selected predetermined precision set. The identified element indicates the precision of each of the motion vectors that characterize the affine motion model. In some embodiments, the precision set to be used is signaled expressly in the bitstream; in other embodiments, the precision set may be inferred, e.g., from the block size, block shape or temporal layer.

Abstract: Methods and apparatuses for video coding are provided. The method includes that a decoder determines whether a disable flag is present in a picture header (PH) associated with a picture, wherein the disable flag specifies whether a coding tool is disabled in one or more slices associated with the PH. Additionally, the method includes that the decoder infers value of the disable flag according to one or more enable flags signaled in a sequence parameter set (SPS) of the picture in response to determining that the disable flag is not present in the PH, inferring, by the decoder.

Abstract: A video coding device may be configured to perform directional Bi-directional optical flow (BDOF) refinement on a coding unit (CU). The device may determine the direction in which to perform directional BDOF refinement. The device may calculate the vertical direction gradient difference and the horizontal direction gradient difference for the CU. The vertical direction gradient difference may indicate the difference between the vertical gradients for a first reference picture and the vertical gradients for a second reference picture. The horizontal direction gradient difference may indicate the difference between the horizontal gradients for the first reference picture and the horizontal gradients for the second reference picture. The video coding device may determine the direction in which to perform directional BDOF refinement based on the vertical direction gradient difference and the horizontal direction gradient difference.

Abstract: Systems, methods, and instrumentalities for affine motion estimation for affine model-based video coding may be disclosed herein. A first motion vector (MV) set including one or more MVs may be derived for a first coding block. The MVs may be control point MVs (CPMVs) and the MVs may be derived by performing affine motion estimation (ME) associated with the first coding block. The first MV set may be added to a recently-estimated MV list. A head of the recently-estimated MV list may be set to the first MV set. The recently-estimated MV list may be empty or may contain one or more previously-added MV sets.

Abstract: Methods and apparatuses for video coding are provided. The method includes that a decoder determines whether one or more reference picture lists are signaled in a picture header (PH) associated with a picture and whether the one or more reference picture lists indicate that one or more slices associated with the picture are bi-predictive. The method further includes that the decoder adds one or more constraints to one or more syntax elements in the PH in response to determining that the one or more reference picture lists are signaled in the PH and the one or more reference picture lists indicate that the one or more slices are not bi-predictive.

Abstract: Methods, apparatuses, and non-transitory computer-readable storage medium are provided for decoding video signals. A decoder receives a bitstream that includes a sequence parameter set (SPS) for video data. The decoder obtains arranged partition constraint syntax elements in sequence parameter set (SPS) level, and the arranged partition constraint syntax elements include intra prediction related syntax elements and inter prediction related syntax elements, and the arranged partition constraint syntax elements are arranged so that the intra prediction related syntax elements are defined before the inter prediction related syntax elements. The decoder decodes the video data based on the arranged partition constraint syntax elements.

Abstract: Overlapped block motion compensation (OBMC) may be performed for a current video block based on motion information associated with the current video block and motion information associated with one or more neighboring blocks of the current video block. Under certain conditions, some or ail of these neighboring blocks may be omitted from the OBMC operation of the current block. For instance, a neighboring block may be skipped during the OBMC operation if the current video block and the neighboring block are both uni-directionally or bi-directionally predicted, if the motion vectors associated with the current block and the neighboring block refer to a same reference picture, and if a sum of absolute differences between those motion vectors is smaller than a threshold value. Further, OBMC may be conducted in conjunction with regular motion compensation and may use simplified filters than traditionally allowed.

Abstract: Methods, apparatuses, and non-transitory computer-readable storage mediums are provided for decoding a video signal. A decoder obtains a reference picture I associated with a video block within the video signal. The decoder may further obtain reference samples I(i,j) of the video block from a reference block in the reference picture I. The decoder may also obtain a first down-sampling filter and a second down-sampling filter to respectively generate luma and chroma inter prediction samples of the video block. The decoder may further obtain a third down-sampling filter and a fourth down-sampling filter to respectively generate the luma and chroma inter prediction samples of the video block when the video block is coded by affine mode. The decoder may also obtain inter prediction samples of the video block based on the third and fourth down-sampling filters being applied to the reference samples I(i,j).

Abstract: An electronic apparatus performs a method of decoding video data. The method comprises: receiving, from the bitstream, a plurality of syntax elements associated with a coding unit, wherein the plurality of syntax elements indicate the coding tree type of the coding unit, and whether the local dual tree mode is enabled for the coding unit; and in accordance with the determination that the coding tree type of the coding unit is a single tree, and the local dual tree mode is enabled for the coding unit: disabling the palette mode for the coding unit when the coding unit has the size equal to or less than a predefined threshold. In some embodiments, disabling palette mode for the coding unit includes: disabling the palette mode for both the luma component and chroma component of the coding unit, or disabling the palette mode for only the chroma component of the coding unit.

Abstract: Systems, methods, and instrumentalities for sub-block motion derivation and motion vector refinement for merge mode may be disclosed herein. Video data may be coded (e.g., encoded and/or decoded). A collocated picture for a current slice of the video data may be identified. The current slice may include one or more coding units (CUs). One or more neighboring CUs may be identified for a current CU. A neighboring CU (e.g., each neighboring CU) may correspond to a reference picture. A (e.g., one) neighboring CU may be selected to be a candidate neighboring CU based on the reference pictures and the collocated picture. A motion vector (MV) (e.g., collocated MV) may be identified from the collocated picture based on an MV (e.g., a reference MV) of the candidate neighboring CU. The current CU may be coded (e.g., encoded and/or decoded) using the collocated MV.

Abstract: Sketch copy mode may be used to code blocks comprising irregular lines, syntax redundancy may be removed from blocks with special characteristics, and/or run value coding may be simplified. The parsing dependencies in palette coding design may be removed. For example, the context modeling dependency of the syntax element palette_transpose_flag may be removed, for example, by simplifying the corresponding context model. The context modeling of the syntax element palette_mode may be removed, for example, by using run-length coding without using context. The syntax parsing dependencies and/or the syntax signaling dependencies that are related with escape color signaling may be removed. A palette table generation process may handle input screen content video with high bit depths, for example, at the encoder side.

Abstract: An electronic apparatus performs a method of coding video data. The method includes receiving, from a bitstream of the video data, a first syntax that indicates an affine motion model enabled for a current coding block, estimating parameters of the affine motion model using gradients of motion vectors of multiple spatial neighboring blocks of the current coding block, and constructing motion vectors of the affine motion model for the current coding block by using the estimated parameters. In some embodiments, constructing motion vectors further includes converting the estimated parameters into control point motion vectors (CPMVs), and adding the CPMVs into a current affine merge candidate list. In some embodiments, constructing motion vectors further includes deriving a motion vector predictor for an affine mode.